Computer stuck in a login loop.

If you have access to another Mac, or a Time Machine backup, or a stable version of OS X on another drive or partition then you've lots of options for sorting this without having to erase the partition with El Capitan installed on it.

If not, you still have quite a few non-destructive options - reinstalling through Recovery Mode for instance will keep your data intact.

Before reinstalling anything, you can attempt to fix the current install. There are a number of options here as well - including resetting the keychain.

First though, I need a little more info:

• Is this an install of El Capitan?
  • If so, did you install El Capitan over Yosemite, or is it a fresh install?
  • Has this happened after installing Beta 1 or after updating to a subsequent beta?
• Do you have easy access to:
  • Another Mac?
  • A stable version of OS X on another drive or partition?
• Can you boot into Recovery Mode (cmd + R at bootup)?

Thank you for your help.

• This is occuring during installation of the second El Capitain Beta.
• The first Beta was installed over Yosemiti.
• I tried to reinstall through recovery mode: Finishes Install But freezes during status bar to start OS
• I do have access to another mac.

Please advise

So the problem now occurs earlier in the bootup-login process. i.e. when you start your Mac now it gets frozen when the progress bar under the Apple logo gets to around 3/4 full?

You no longer get to a log-in screen?

If that's the case then putting the problem Mac into Target Mode (Boot up holding cmd + T) and connecting it via firewire or thunderbolt cable (USB might not work) to the other Mac will be the first step. You should then see the problem Mac's internal drive appearing as an external drive on the other Mac.

Do you have everything you need to get this far?

Hey Max,

This was always my original problem. The looping I described was my attempts at starting in safe mode. Sorry I should have been clear at the begining. If I start in safe mode I get to the log in.

That's okay. Can you connect to the other Mac in Target Mode as described above?

Got my hands on a thunderbolt cable to try the Target Mode as described. Didnt work. Then I found this below.

"Target Disk Mode is not supported on Macbook Air that lack a true Thunderbolt port. The Mini DisplayPort is purely a video out port, and cannot be used for data transfer, despite the identical connector.

The only supported option for transferring data between two Macbook Air, using a wired connection, using Migration Assistant, is through ethernet. Since both models of the Macbook Air do not have an ethernet port, you will need to purchase the Apple USB to Ethernet Adapter for the older model Macbook Air which does not have a Thunderbolt port, and an Apple Thunderbolt to Ethernet Adapter for the newer model which supports Thunderbolt."

Okay, I don't think it's worth buying a new adaptor. There are other options than Target Mode.

It sounds like you may have a kext left over from Yosemite that is causing the problem with booting into El Capitan.

The easiest thing to try for that is to temporarily disable SIP by booting into recovery mode (cmd+R):

Utilities > Security Configuration > uncheck "Enforce System Integrity Protection"

Then try booting normally to see if it completes.

I logged into recovery mode and followed your instructions to uncheck the security configuartion option. After a restart this didnt give me the same results under normal and safemode startup.

Loging in through safe mode I was able to get a little further into the sytem by clicking the "?" on the keychain login screen. This brings up an explanation where I can click "open keychain access for me" which then will also bring up the top window menu allowing me to go into sytem preferences. In system prefernces It seems I have full access including telling it to startup in target mode.

Max,

My Statement above has a serios typo in it.

I logged into recovery mode and followed your instructions to uncheck the security configuartion option. After a restart this gave me the same results as before not fully loading in normal startup and lopping in safemode startup.

My next question is what can we try since I found a workaround to get me into system preferences, using the mehtod above?

Hi Clifford,

Target mode is a non-starter - we don't need to think about that any further.

The workaround to get into System Preferences was a good find. If you go into iCloud (maybe you also need to log into iCloud there) and un-tick "Keychain", that may help.